This invention relates generally to apparatus and methods for reducing the risk of bedfast patients developing decubitus ulcers.
It is well known that patients who are confined to a bed or chair for extended periods of time are at risk of developing decubitus ulcers, i.e., pressure sores, or bed sores as they are more commonly known. These ulcers are often seen to develop within soft tissue that is compressed between a bed or chair surface and a patient""s weight-bearing bony prominences, the compressed tissue being at least partially deprived of oxygenated blood flow. A continued lack of blood flow, and resultant lack of oxygen, can result in cell death which may be evidenced in the form of pressure sores. Pressure sores do not develop immediately, but rather form over time, with the development speed depending on a number of factors including the firmness and friction of the supporting surface against the patient""s skin, the patient/ambient temperature, the amount of moisture in contact with the skin, and the health and susceptibility of the skin due to age or illness.
One venerable and generally accepted means of reducing the risk of decubitus ulcer development in bedfast patients is to turn them regularly, usually at approximately two hour intervals. For example, a patient in a back rest position might be periodically rolled to one side or the other, such motion helping to maintain blood to flow to soft tissue that is under compression. Similar strategies are employed for patients that are confined to a chair for long periods of time. Obviously, an assisted-movement strategy relies to a large extent on the vigilance of the (often harried) attending staff to insure that the patient is properly relocated. Further, it is far too easy for the busy care giver to let the time for turning the patient slip by in the press of other daily emergencies. To the extent that the caregiver is too busy or forgets to perform this service, this method can fail to achieve its purpose. Further, this sort of strategy can be counterproductive for use with the patient that has some capacity for self movement.
More particularly, the process of moving a patient to another position is admittedly disruptive to the patient and this is especially true at night, since the patientxe2x80x94if he or she were sleepingxe2x80x94will be awakened for the purpose of relocation. The typical two-hour movement interval must be observed around the clock if the method is to be effective, so it is necessary to rouse the patientxe2x80x94who might be sleeping soundly at the timexe2x80x94to make the required adjustment in position. Further, this adjustment might not have even been necessary if the patient had recently moved of his or her own volition. Thus, in many situations it would be advantageous for the caregiver to know if and when the patient last moved his or herself. Then, if the last movement were within a prescribed period of time, it might be possible to spare the patient an unnecessary interruption in his or her healing sleep. The caregiver would then relocate the sleeping patient, only if that relocation were actually required. Further, knowing which patients do not need to be moved could result in a substantial savings in labor costs, as the time that would otherwise be devoted to moving the patient that did not actually need to be moved could be productively applied elsewhere. That being said, as useful as this sort of information might be to the health care provider, however, the present state-of-the-art in patient management does not provide this sort information.
Generally speaking, there are two broad inventive approaches to dealing with decubitus ulcers: mechanical and medicinal. The mechanical approach is aimed at preventing the occurrence of bed sores through the use of a specialized mattress, pad, or other arrangement, which is designed to lessen the weight-pressure that is brought to bear on the patient""s bony prominences. These devices might be either static (e.g., foam, air, or water mattresses) or dynamic (e.g., compartmentally inflatable mattresses that dynamically shift the locus of support pressure under the patient in response to the patient""s movements). Examples of inventions in the prior art that are generally concerned with this subject matter are U.S. Pat. Nos. 4,425,676, 5,926,884, and 5,072,468, the disclosures of which are incorporated herein by reference.
On the other hand, the medicaxe2x80x94or second inventivexe2x80x94approach is concerned with the development of medicinal compounds and methods of treating the ulcer after it occurs. This approach is obviously useful but reactive, rather than proactive, as it attempts to minimize the damage occasioned by the ulcer after it has formed.
General information relating to mats for use in patient monitoring may be found in patent application Ser. No. 09/285,956 filed Apr. 2, 1999, now U.S. Pat. No. 6,307,476, the disclosure of which is specifically incorporated herein by reference. Additionally, U.S. Pat. Nos. 4,179,692, 4,295,133, 4,700,180, 5,600,108, 5,633,627, 5,640,145, and 5,654,694 (concerning electronic monitors generally) contain further information generally pertinent to this same subject matter, as do U.S. Pat. Nos. 4,484,043, 4,565,910, 5,554,835, and 5,623,760 (switch patents), the disclosures of all of which are all incorporated herein by reference.
Heretofore in the patient monitoring arts there has been no apparatus or method aimed specifically at reducing the risk of bed sores in a semi-invalid patient, i.e., the patient who at least occasionally moves without assistance. With a semi-invalid patient, assisted repositioningxe2x80x94whether manual or mechanicalxe2x80x94should only take place if the patient has not moved for some particular period of time. This, of course, suggests the need for a method and apparatus for monitoring the patient so that the time when he or she last moved can be determined. Further, the amount or magnitude of the patient""s movement should also be monitored so that a repositioning will still take place as-scheduled if the patient has moved during the previous time period, but the amount of movement has not exceeded some particular threshold level (i.e., whether or not a significant relocation or movement has occurred). Finally, there is a need for an apparatus that can monitor and report the overall amount of patient self-induced and/or caregiver assisted movement, so as to give the caregiver (or that person""s supervisor) some estimate of the amount of movement by the patient in the bed.
Heretofore, as is well known in the patient monitor arts, there has been a need for an invention to address and solve the above-described problems. Accordingly, it should now be recognized, as was recognized by the present inventors, that there exists, and has existed for some time, a very real need for a system for monitoring patients that would address and solve the above-described problems.
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.
In accordance with a first aspect of the instant invention, there is provided a sensor for use in patient monitoring situations, wherein the level of patient motion is tracked over a given period of time for purposes of determining whether or not that patient has exhibited sufficient motion to merit eliminating a scheduled assisted relocation to a new position. The instant device operates to sense the length of time since a patient has last moved from a previous sitting or lying position. If the patient has not moved during, for example, the prior two-hour period, it is preferred that the nursing staff be notified that it is time to manually reposition the patient. On the other hand, if the patient has changed position within the specified window, the device will note that fact and withhold its reminder to the nurse or other caregiver that the patient needs to be moved at the next scheduled relocation time, thereby eliminating the need in some cases to rouse the patient from an otherwise sound sleep. In either case, the instant invention operates to reduce the risk that a patient will develop bed sores by helping ensure that the patient is manually moved as frequently as is medically necessary, but no more often than is actually necessary.
In accordance with another aspect of the instant invention there is provided an electronic monitor for use with a patient sensor which is designed to monitor the patient""s position and calculate his or degree of activity in the chair or bed. In the preferred embodiment, the monitor consists of a microprocessor in electrical communication with a patient sensor (discussed below). The microprocessor will be equipped to ascertainxe2x80x94by reference to the attached sensorxe2x80x94an initial position of the patient within the bed. Once an initial position is determined, the monitor will then continue to watch the patient""s position, looking for xe2x80x9csignificantxe2x80x9d changes in that position. If such a change has not occurred before the passage of some predetermined time interval, the monitor will enter into an xe2x80x9calarmxe2x80x9d or signaling state. Depending on the settings selected by the operator, the monitor might emit an audible alarm, signal a nurses station, initiate a visual alarm (e.g., a flashing light), etc., that would serve warning to the caregiver that it is time to turn the patient. Needless to say, although the preferred embodiment of the instant invention calls for a device that gives notice to the care giver when the patient needs to be moved, the invention disclosed herein could as easily be modified to notify the caregiver when the patient does not need to be moved.
On the other hand, if the patient demonstrates a significant change in position prior to the expiration of the predetermined time period, the CPU in the electronic monitor will note that fact and reset the timer, preferably to its initially specified time interval. This change in position may or may not be accompanied by the sending of a signal to the care-giving staff to inform them of that fact. The CPU will then continue to monitor""s the patient""s position via the sensor until either the current time period expires or the patient moves again.
Broadly speaking, the instant invention consists of two functional components: a position sensor and an electronic monitor. In the preferred embodiment, the electronic monitor and sensor will be separate devices. However, it is certainly possible, and well within the skill of one of ordinary skill in the art, to combine these two functions into a single operating unit. That being said, preferably, and as described below, two separate modules will be utilized. In broadest terms, the position sensor component generates signals in response to the location or orientation of the patient in the bed or chair. The electronic patient monitor senses and interprets the signals from the position sensor and, in the preferred embodiment, handles the arming/disarming of alarms and communications with the nurses station.
The sensor portion of the instant invention, which might be any one of a number of different devices, must at minimum be capable of sensing a change in the patient""s position, location, or orientation within a bed or chair. Examples of devices that might be suitable for use with this invention include a pressure sensitive bed or chair mat, a temperature sensitive bed or chair mat, pressure sensitive mats placed underneath the feet of the hospital bed, accelerometers in communication with the springs of the bed, infrared motion detectors, etc.
A minimal requirement of the electronic monitor is that it be able to sense patient position information as provided by the sensor. Additionally, it must be able to track the passage of time in at least some rudimentary fashion, so as to determine the time interval between patient movements. In the preferred embodiment, the monitor will include a microprocessor which can implement the logic described below and, additionally, can function as a clock if need be. Finally, in the preferred embodiment the monitor will be able to use the sensor information to differentiate between body movements that are only slight shifts in position and other movements that actually result in a change the patient""s weight supporting points.
Turning now to various embodiments of the instant monitor, according to a preferred embodiment of the instant invention, there is provided a monitoring device substantially as described previously, but wherein a patient movement threshold is established such that only xe2x80x9csignificantxe2x80x9d movements are sufficient to cause the device to reset withhold notification of the nursing staff to turn the patient, thereby letting the patient continue to rest.
According to a further preferred aspect of the instant sensor, there is provided a monitoring device substantially as described previously, but wherein a patient movement threshold is established as described previously, but wherein the xe2x80x9csignificantxe2x80x9d movement must be maintained for some period of time. That is, if a patient moves significantly, but that movement is only temporary (e.g., for less than ten minutes), after which the patient returns to nearly the same position, the monitor will not be reset, and the staff will be called to turn this patient on the normal schedule.
According to another aspect of the instant invention, there is provided a patient monitor substantially similar to that described above, but wherein the accumulated timed movement of the patient is monitored. Thus, if the patient is sufficiently restless but no single movement event amounts to a significant relocation, that patient might still not need to be turned as they have not accumulated enough time in any one position to cause a problem. A preferred embodiment of the instant invention will detect and respond to that sort of condition.
According to still another aspect of the instant invention, there is provided a patient monitor substantially similar to that described above, but wherein the motion time interval (i.e., xe2x80x9cturning timexe2x80x9d, hereinafter) is not a fixed interval but is adjustable according to parameters specified by operator. Many other variations are possible and have been contemplated by the instant inventors.
In the preferred embodiment the sensing device will be a pressure-sensitive bed mat which is placed underneath a weight-bearing point of the patient. The mat will preferably be designed to sense at least one point of contact along its length, i.e., it will be able to determine the distance from one of its ends to the nearest point where the patient""s weight compresses the mat. Obviously, for a completely motionless patient, this parameter (distance-to-contact-point) will be unchanging. However, if the patient rouses and moves, the point of contact will changexe2x80x94at least during the time that the patient is moving. It may be that the patient will completely remove his or her weight from the mat before settling back down again. If the patient is out of bed for more than a brief time that would typically be sufficient reason to reset the movement timer. However, the more likely scenario it that the patient will simply roll from one side to the other without ever completely removing weight from the mat. In that case, the monitor will note the change in patient position-as measured by the change in distance to nearest contact pointxe2x80x94and, depending on its parameter settings, determine whether that movement is significant and, thus, merits resetting the movement timer. Finally, it should be noted that one advantage of using a mat-type arrangement as described here is that the mat can then double as an exit mat, if that is desired.
According to a further embodiment, there is provided an electronic monitor as described above, but wherein a the electronic monitor begins to sound a local warning a predetermined amount of time before it signals the nurses station. That is, in the preferred variation of this embodiment the electronic monitor might begin to make a relatively unobtrusive noise such as a chirp or beep (say) five minutes before the nurses station was to be notified. This noise might be enough to rouse the patient so as to cause him or her too turn without assistance. On the other hand, if the patient does not move at the predetermined time the nurses station will be signaled. This embodiment has the advantage of helping patients to learn to turn themselves.
The foregoing has outlined in broad terms the more important features of the invention disclosed herein so that the detailed description that follows may be more clearly understood, and so that the contribution of the instant inventors to the art may be better appreciated. The instant invention is not to be limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and of being practiced and carried out in various other ways not specifically enumerated herein. Further, the disclosure that follows is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. Finally, it should be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting, unless the specification specifically so limits the invention.
While the instant invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.